How To: Jailbreak iOS 4.2.1 & Unlock iPhone with Ultrasn0w too!

Posted February 4, 2011 by Charlie Pryor in iDevice

NOTE: THIS APPLIES ONLY TO GSM iPHONES! The CDMA model (Verizon) IS NOT SUPPORTED!

Many people aren’t happy with their carrier, or the normal carrier the iPhone comes for. They opt to use it with another carrier. In the case of the United States, many people opt to use the iPhone with T-Mobile (the only other GSM carrier in the United States) rather than AT&T.

This tutorial will guide you through the process of updating to the latest firmware, and being able to jailbreak while retaining the older modem firmware (baseband). By doing this, you’ll be able to do what’s called “Unlocking” the iPhone, enabling it’s use on another carrier besides the normally supported one.

This is also very useful if you want to travel internationally, and wish to use the iPhone on a carrier outside the country (or sell it outside the country).

If you have no intention of leaving your carrier, or do any international travelling with your iPhone, you do not need this tutorial. You can simply jailbreak like normal by following the guide HERE.

Okay then… so, if you are still reading this, that means you want to Unlock the iPhone for later usage. Follow the steps below to go forward with this process.

(Note: Use this guide at your own risk! I’m not responsible if something goes wrong with your device. This guide is for informational use only, and can be used or not used for your benefit).

OKAY… Let’s begin the Tutorial: THIS VIDEO CAN SHOW YOU HOW STEP-BY-STEP. The video is following along with the instructions below. Please use these along with the video if you get lost. – For questions on the process, please use our facebook page (where we help people directly, one on one).

IMPORTANT: 3Gs Unlockers: If you want to upgrade to 4.2.1, Use PwnageTool to preserve your baseband and create custom firmware.

Step 1: Update iTunes to iTunes 10.1.2

Step 2: Download TinyUmbrella from here and Greenpois0n from HERE.

Step 3: Connect the iPhone to your Mac.

Step 4: Start up TinyUmbrella. Be sure that the software can see your iPhone, and that everything within the program is reading your iPhone as connected (and that it sees the baseband).

(NOTE: Windows users will need to start this software as administrator. If any firewall prompts come up, be sure to allow access to everything that has to do with TinyUmbrella).

Step 5: Make sure Cydia or TinyUmbrella has an SHSH of the latest firmware. If you have never used TinyUmbrella or Cydia before, click the “Save my SHSH” button. If you have used them before, but are unsure, just click it anyways. Once you are sure you have saved SHSH blobs… proceed to the next step.

STEP 6: Click “Start TSS Server” in TinyUmbrella. This will alter your host file and allow the process to work. (This also closes iTunes).

Step 7: Open iTunes. It’s a good idea to backup your iPhone here, just in case.

Step 8: When offered the update from iTunes, click “Download and Update”

The installation may take some time…. be patient.

Step 9: Now, when your iPhone boots up, you should get a 1013 error. This is good, because it means your baseband was not updated!

Step 10: Put your DEVICE in DFU MODE! – With your iPhone 4 still plugged into iTunes, Hold Power and Home until the screen goes black. Count to 2 slowly, then release POWER but CONTINUE Holding HOME for another 2 or 3 seconds. If you release Home and your screen is still black, you did this correctly. If your phone goes back into recovery mode, try again until you get it into DFU.

STEP 11: Open Greenpois0n. – Start your jailbreak now, while the device is in DFU mode already. You do not need to activate or even boot up normally to get Greenpois0n to work.

The Jailbreak software will do it’s thing, and the device will boot normally as it’s supposed to. iTunes will recognize it, and prompt you to set it up.

STEP 12: Unless absolutely necessary, Set up your device AS A NEW PHONE.

Now, check to see if the process worked for you (it did, of course).

Go to: Settings.app > General > About. From here, locate your modem firmware (baseband)

If your baseband remains the same (01.59.00), then you are good to go, and can unlock with ultrasn0w 1.0-1! YAY!

You can now Follow the last part of our Other tutorial, where you install Cydia, using the Loader.app on your home screen.

Final Step: Install “ultrasn0w 1.0-1″ in Cydia to unlock your iPhone as you have before.

NOW YOU’RE DONE! You should be able to use your iPhone with any GSM carrier now! YAY!

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About the Author

Charlie Pryor

Charlie is a technology nut, and a big fan of Apple products. While attending college at Grand Valley State, he uses much of his free time every day answering questions on facebook. He founded HotTips! back in January 2010, and believes that anybody can learn anything if they have the right teacher.